Apparatus for controllable in-situ combustion

ABSTRACT

A system of apparatus for controllable in-situ combustion in subterranean hydrocarbon bearing formations containing bitumens with simultaneous production and recovery of energy sources supplying the mechanical and thermal energy required for the insitu combustion and operation of the facilities involved.

o mted States :1 tent [1 1 [111 3,772,881

Range Nov. 2, 1973 [54] APPARATUS FOR CONTROLLABLE 3,238,719 3/1966Harslem 60/3955 llN-SKTU COMBUSTION 2,959,005 11/1960 2,636,345 4/1953[75] Inventor: Hans Lange,W1etze, Germany 1,415,730 5/1922 943,08212/1909 [73] Asslgnee. Deutsche Texaco Aktiengesellschaft, 2,734,5782,1956

Hamburg Germany 2,823,752 2/1958 Walter 60/3955 [22] Filed: Feb. 23,1972 [21] App]. No.: 228,677 Primary Examiner-Carlton R. Croyle RelatedUS. Application Data Division of Ser. No. 43,547, June 4, 1970, Pat. No.3,700,035.

References Cited UNITED STATES PATENTS 8/1969 Aguet 60/3955 AssistantExaminer-Warren Olsen Att0rney-Thomas H. Whaley et a1.

[5 7] ABSTRACT A system of apparatus for controllable in-situ combustionin subterranean hydrocarbon bearing formations containing bitumens withsimultaneous production and recovery of energy sources supplying themechanical and thermal energy required for the in-situ combustion andoperation of the facilities involved.

6 Claims, 4 Drawing Figures PATENTEDHBV 20 I975 3,772,881 SHEET 10F 4FIG.

PATENTED NOV 2 0 I975 SHEET 2 UP 4 PATENTEUNUV m1 m5 SHEET 3 BF 4 H Od+N C 0 {l 51 BAG PATENTED MW 2 0 I973 SHEET U BF 4 FIG. 4

APPARATUS FOR CONTROlLlLABlLlE IN-SITU COMBUSTION This is a division, ofapplication Ser. No. 43,547, filed June 4, 1970, now U.S. Pat. No.3,700,035.

FIELD OF THE INVENTION DESCRIPTION OF THE PRIOR ART In-situ combustionin subterranean hydrocarbon bearing formations use low hydrogenpetroleum residues as fuel for the combustion front, and the heatdeveloped from their combustion produces additional combustional gasessuch as carbon monoxide and hydrogen which together with the dissolvedhydrocarbon gases and the combustion product, such as carbon dioxide,escape from the production wells in gaseous form. The heat from thecombustion and the heat contained in the steam formed in the bum-outmatrix behind the combustion front flows before the combustion frontheating the hydrocarbon bearing reservoir and reducing the viscosity ofthe hydrocarbon therein and displacing the hydrocarbon toward theproduction wells.

The combustible gas mixtures and the carbon dioxide escaped enter intopressure-resistant fireboxes or pressure-resistant furnaces of a specialsteam boiler, are burnt with evolution of heat by means of highlyconcentrated oxygen with residual nitrogen or of air used in heavyexcess, and produce forms of energy, such as steam or hot combustiongases under pressure, that may supply energies to the facilitiesinstalled above ground and may also partly be introduced into thedeposit through injection boreholes. v

The generation of combustion heat in the underground deposit and theadditional production above ground of different forms of energy that arepartly and temporarily supplied to the deposit from above ground createa more comprehensive effect upon the content of the deposit. Theaddition of high-pressure steam in quickly variable amounts leads to aneven spreading of the combustion front, facilitates the start of theprocess in each injection borehole, and increases the yield from thedeposit. The use of carbon dioxide recovered in minor quantities fromthe condensation plant improves safety in the injection boreholes andalso has a favorable influence upon the yield. It is advantageous,therefore, to combine all conditioning agents above ground so that theycan be produced, applied, and controlled with the operation of thesurface plants. The activated combustion gas can easily be varied in itscomposition and adjusted to operating conditions at any given time. Inthe starting phase, it may temporarily consist almost exclusively ofsteam with little oxygen; in the actual burning phase, it may containplenty of oxygen with small quantities of residual nitrogen and carbondioxide. The formation of steam may be either reduced by throttling downthe supply of fuel gas, or it may be increased to provide mechanicalenergy for covering other energy requirements in the production field.

It is, therefore, an object of the invention to use various processelements in the deposit and in the surface installations for makingavailable all necessary operating agents at short notice and in acontrollable manner. There are several possibilities of variation, thusallowing of several application techniques. Moreover, the plant andequipment involved can be readily transported owing to their lightweight and small dimensions, thus facilitating adjustment to theconditions in oilfields being opened out.

SUMMARY This invention relates to system of apparatus for controllingin-situ combustion using highly concentrated oxygen with residualnitrogen and a partial and/or temporary supply of superheated steamtogether with simultaneous production of energy for the operation of thenecessary above ground facilities.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a diagramatic cross-sectionof the firebox.

FIG. 2 is a diagramatic cross-section of high-pressure steam boiler.

FIG. 3 is a general illustration of the overall layout.

FIG. 4 is a diagramatic cross-section showing a double-walled steamboiler.

DESCRIPTION OF THE PREFERRED EMBODIMENT When using high pressures ofinjection into the borehole, such as for steam coming from a closedsystem of tubes, it is envisaged that the pressure of the feed waterflowing in the annular space of the double-walled firebox or steamboiler should be smaller or slightly higher that that prevailing in thecombustion chamber, and only after leaving the annular space should thefeed water be pumped up to the pressure required for injection into theborehole.

The invention achieves these objects mainly by producing hothigh-pressure steam in the combustion chamber, injecting water into apressure flame from an open system of tubes, and by additionallyproducing high-pressure steam in a closed system of tubes. The two typesof steam may be used both for injection into the deposit and forsupplying surface installations. Moreover, a mixture of separated drycarbon dioxide and residual nitrogen may be introduced at combustionchamber pressure, or at increased pressure after passing through acompressor, into the deposit via special pipes in the injectionboreholes.

Technically, these requirements are met by using means known per se,such as a firebox or a steam boiler provided with a high-pressurecombustion chamber. Particularly suitable is a firebox or steam boilersurrounded by a double wall forming an annular space through which acooling medium, such as the feed water for the firebox or steam boiler,is passed, the surface area of the interior wall being enlarged at theside of the flowing feed water so that the interior and exterior wallswill always have the same temperature and thus the same expansion,enabling them to take up high pressure from within the combustionchamber.

According to the invention, when using highly concentrated oxygen atvery high pressures up to and above 200 atmospheres, only a small volumeof combustion gases will be present in the combustion chamber.Alternatively, at medium pressures ranging from 3 to atmospheres, airwill be used in heavy excess over the amount of air required to providecombustion of the fuel, and part of the air from the compressor for thecombustion turbine before the steam boiler will be branched off for theoxygen plant. In both cases, however, flue gas is taken from thecombustion chamber and steam is taken from the high-pressure steamsection for two different purposes, the flue gas and the steam eachsimultaneously doing two different jobs above ground and in the deposit.The temperature of a flame is known to increase as the pressure of thegases in the combustion chamber and the oxygen content of the combustionair increase. The shorter the period of time during which a givenquantity of oxygen is converted to combustion gas, and the smaller thecombustion chamber volume in which this conversion takes place, thehigher the flame temperature will be. The pressure flame used in themethod of the invention meets all conditions that will increase theflame temperature at a high rate of combustion. Thus, it is a flamemaintained in a small-volume combustion cham ber. Its characteristicfeature is an extremely high flame temperature with an extraordinarilystrong radiation of heat, which cannot be cooled down sufficiently by asystem of water and steam tubes even with normal circulation of thecombustion gases. Almost invariably, film evaporation will occur in thewater tubes, which will further deteriorate the cooling of the flame andwill allow the temperatures to rise to an undesirable degree. To thatcase, the flow of feed water through the annular space between the twowalls will scarcely lower the temperatures in these walls sufficientlyto maintain adequate mechanical resistance values for the material ofthe walls.

To eliminate these disadvantages, wateris injected into the flames sothat a radiation-absorbing envelope of steam is formed around the flameswhich will effect an inertialess reduction of the flame temperature byevaporation of the water and will considerably diminish the effect ofheat radiation on the walls of the combustion chamber. Heat distributionis further improved by providing in the combustion chamber and near thedouble wall of said combustion chamber a tubemounted wall havingcircular openings to permit circulation of the cooled-down steam.

In such steam boilers or fireboxes having pressureresistant features, itis also possible to withdraw from the combustion chamber, from acondensation plant, or from a closed system of tubes such combustionproducts as carbon dioxide with residual nitrogen and steam in thedesired temperature range, or cold dry carbon dioxide with residualnitrogen, as diagrammatically shown in the attached drawings.

The simplest case is illustrated in FIG. 1, when the oxygen with a smallamount of residual nitrogen is available at such a high pressure that itcan be forced into the deposit at against the pressure of the deposit,using an additional pressure of 50 to 75 atmospheres, a very small partstream of oxygen stream is introduced at its full pressure into adouble-walled pressure-resistant firebox to be burnt with hydrocarbonsto form carbon dioxide with residual nitrogen and steam. Since thecombustion of hydrocarbons with highly concentrated oxygen leads to veryhigh temperatures endangering the steel construction material of thefirebox, water is injected at 15 and 16 through injection tubes 6 and 11directly into the flame in combustion chamber 18. The injection waterevaporates immediately thus reducing the temperature in the combustionchamber. To be able to resist the high pressures encountered, thefirebox is surrounded with a double wall 1 and 2, enclosing an annularspace 3. For cooling the two walls, the slightly preheated injectionwater is introduced into annular space 3 at 13. At 14, the water can beseparated into two part streams and passed to the injection tubes viathe inlet openings 15 and 16. Inlet 15 provides an upper injection watersupply with injection openings 6 and inlet 16 provides a lower injectionwater supply with openings 1 1. The upper injection openings 6 form thesteam envelope for protecting the combustion chamber, and with the lowerinjection openings 11 the outlet temperature of the combustion gases andvapors is adjusted, to the necessary temperature for entry into theinjection borehole 28. The tubesupporting wall 4 has openings fittedwith steam injectors at 17 and further injectors 12 in the annular space5 permitting circulation via outlet 10 of part streams from combustionchamber 18 to provide balanced temperature conditions.

Oxygen 8 and hydrocarbon 9 enter into the burner (not indicated) at 7and leave the combustion chamber as combustion products together withsteam from the injection water at 19, any entrained solids being keptback by small refractory bodies 31, which may consist of sintered ironor small ceramic bodies having large pores, to prevent obstructions inthe deposit. Through sluices 29 and 30 the bodies 31 can be replacedwithout interrupting operations. A completely unchanged stream fromoutlet 19 is introduced into the interior corrosion-resistant tube 24 ofthe injection bore. After cooling, a smaller part stream of dry carbondioxide with residual nitrogen passes into the annular space 27 ofborehole 28 and temporarily, alternating with the oxygen, into theannular space 25 of the ascending tube 26. Similarly, the hydrocarbon23, alternating with the combustion products and steam 21 and 22, passesinto the interior tube 24.

FIG. 2 shows an additionally installed closed system of tubes 32 whichis used as a high-pressure steam boiler. Since the interior wall 2 ofthe double wall is very closely covered with tubes, only small amountsof radiation and conduction heat can reach this wall, so that a specialtube-supporting wall is not required. The water for the high-pressuresteam boiler entering at 13 and the injection water pass through annularspace 33 for cooling the double walls and enter the two systems of tubesat 33 and 35 at a controlled rate.

Combustion of the oxygen and hydrocarbons with cooling of the flame aswell as the entry of the combustion products formed into the bore areeffected in the same way as shown in FIG. 1. However, the amount of fueland oxygen must be increased to such an extent, that the steam leavingat 39 can be used for operating steam turbine 36 and power generator 37,the waste steam being condensed in condenser 38. Opening 34 is used forintroducing water for temperature regulation.

In FIG. 3 compressed air in the pressure range of 3 to 15 atmospheres isused as oxidation agent for combustion chamber 18, while highlyconcentrated oxygen with residual nitrogen is produced in an oxygenplant 57 on the oilfield and brought to the required pressure by meansof high-pressure compressor 59 so that it can be introduced into thedeposit in sufficient quantity through injection borehole 28.

The overall layout shown in FIG. 3 provides for a complete coordinationof the methods of operating the in-situ combustion in the deposit withthe supply of installations above ground. It will be desirable, however,to supplement the equipment shown in FIG. 3 by a firebox as shown inFIG. ll, so that in the event of breakdowns or when starting the in-situcombustion no major pause or delay can occur during which the fire inthe deposit might be extinguished.

Two separate plants are installed for the energy production, accordinglythe steam boiler with its pressureresistant furnace is equipped forusing compressed air, part of which serves for the production of oxygen.The second source of energy is based on steam; the steam has a pressuresufficient for injection into the borehole and is also used continuouslyor temporarily for driving a turbogenerator 36 whose energy output isused for operating installations above ground.

The inter-connected plate elements, air compressor 49 and combustionturbine 50, are combined with a steam boiler forming the combustionchamber. 85 percent :t 20 percent of the air is passed into annularspace 44 between walls 2 and 43, where it is preheated. Then the air ispassed through annular space 44to point 7 and is mixed with thehydrocarbons 9 at the outlets to the burner (not indicated). The mixtureis burnt in combustion chamber 18 using a heavy excess of, air.

From line 47, a part quantity of 30 percent percent of the compressedair is branched off to oxygen plant 57, supplementing the quantity ofair from air compressor 56. Thus, there are two separate sources of airfor the oxygen plant, each of which can provide about 50 percent of thetotal air required.

The combustion gases formed in combustion chamber 18, being products ofthe combustion of the hydrocarbons with compressed air, have a hightemperature. These gases are exhausted from the combustion chamber 18and are passed through combustion turbine 50 and thereafter passed intoheat exchanger I and condenser I 52 wherein they are cooled by waterprovided from water treatment plant 55. The gases and condensed waterare passed to condenser II, 53. The condensate from condenser II ispassed through pipe 15 with openings 6, having been cooled to such anextent that no film evaporation can occur in pipes 32. The injectionwater, introduced through inlet 40 to pipe system 41 leading to theinjection openings 42 into the combustion chamber is controlled so thatthe water entering the evaporator 45 at 46 is evaporated and the steamis drawn off through pipe 39, having the desired temperature both forthe injection borehole 28 and for steam turbine 36 which may, forexample, drive the power generator 37. The volume of steam formed by theinjection water replaces the air from air compressor 49 branched off foroxygen plant 57, thus resulting in a total gas volume or additionalsteam volume for combustion turbine 50 driving power generator 51.

The waste steam from steam turbine 36 is partially condensed in heatexchanger II (point 38, combined with condenser III), and the residualsteam in condenser III, point 38. The condensate is passed via pump 2into heat exchanger I, point 52, which receives its heat from the wastegases of the combustion turbine 50. In heat exchanger I, point 52,combined with condenser I, the feed water from feed water treatmentplant 55 introduced via pump 3 and the condensation water from point 38introduced via pump 2 are heated, the water for the closed system oftubes 32 entering pipes 32 at 34 as a part stream. The steam from theinjection water from combustion turbine 50 having an inlet temperatureof about 450 C. is cooled in heat exchanger I, point 52, condensed incondenser I, and mixed via pump 4 with part of the feed water 55 in condenser II, point 53. The heat from heat exchanger II and condenser IIIis further used at point 38 for heating the wet petroleum recovered fromthe deposit, thus separating oil and water. The separated water can beused in other boreholes for flooding purposes. Parts of the condensateobtained at 38 can be introduced without heating into annular space 3between walls 1 and 2 at point 13 via pump ll.

The combustion gases from chamber 13 and steam generated by injectingwater into the flame will enter the heat exchanger I (position 52) vialine 48 and combustion turbine 50. The temperature of the gaseousmixture decreases from 950 to 450 C. while passing combustion turbine50. Loss water from apparatus 55 for dehardening the feeding water alsowill enter the heat exchanger 52. The inside temperature of chamber 18will be controlled furthermore by injecting feeding water at 34.

Inside the condenser II (position 53) especially near its upper warm endgaseous products, like nitrogen, oxygen, and carbon dioxide will escapefrom the condensate. A mixture from carbon dioxide and remainingnitrogen will be delivered at the bottom of condenser 53 and supplied tothe injection borehole 28.

Owing to the cold water the carbon dioxide and residual nitrogen arealso obtained cold containing very little steam, it may be considered inthe borehole as dry carbon dioxide which is not corrosive even if itmust be pressurized. With the same degree of cooling the oxygen may alsobecome non-corrosive after compression.

Air from air compressors 49 and 56 is used for producing oxygen in plant57, almost all of the nitrogen escaping at 58. In compressor 59 theoxygen is sufficiently pressurized for passing into the deposit via theinjection borehole. Also in the case of combustion chamber 18 usingcompressed air as oxidation agent for the hydrocarbons from the deposit,the injection borehole 28 is supplied with the necessary agents as shownin FIG. ll.

The double-walled combustion chamber with its walls 1 and 2 alsoreceives part of the feed water for reducing the temperature direct fromcondenser III, point 38, at a pressure below that of combustion chamber18. The feed water enters the annular space 3 at 13, leaves it at 60, isbrought to the pressure of the closed system of tubes 32 by means ofpump fill, and passes into the closed system of tubes at 62.

In combustion chamber 18, the tube-supporting wall 4 is provided withinpipe wall 43 so that in annular space 5 with injectors 112 and 17, acirculating effect can be achieved at ill by means of the injectionwater introduced at 16 to create balanced temperature conditions.

This special double-walled steam boiler thus supplies the injectionborehole 28 and turbines 36 and 50 so that a coherent system has beenprovided and a maximum of conditioning agents is available forcontrolling the in-situ combustion.

FIG. 4 is a diagrammatic drawing of a double-walled steam boiler havinga multi-stage burner and pressureresistant upper and lower cover plates.This design is suitable for higher pressures even at temperatures of 300C.

For transport from one oilfield to the other, the exterior wall can beremoved so that the remaining low weight of the interior wall with itsinstallations permits its transport as a unit. The lower rings 66 aresuitably parted and fitted to the walls 1 and 2.

Thus, the exterior wall 1 and the interior wall 2 have inner and outerrings 66 at the top and bottom. The upper ring 82 has openings only forbolts 63.

The upper and lower cover plates 68 are welded to the inner rings 66 and70.

By means of screw joints 63 and 64 the upper counter-ring 82 is pressedon the soft iron rings 65 and rings 66 to form a tight seal.

Additional seals are provided by rings 67 and 71.

The flange openings 69 are screwed to the upper and lower cover platerims 68. The burner with its inner opening 74 and its outer opening 72is welded or screwed to the upper flange opening.

The combustible gases enter at 9 and the oxidation agent at 44. Theoxidation agent passes from 47 into the annular space 44 formed by walls2 and 43. It passes between walls 72 and 73 and is mixed at ring burners75 and 78 or, respectively, 79 and 81, at the conical outlet 80.

The burner having several ring burners 75 and 78 is able to produce avery long downward flame through the vertical openings 79 and 81. Thefeed water is introduced into annular space 3 at 13 and leaves it at 60.

' The bottom of the boiler casing corresponds in design to the top part.The top and bottom of the boiler casing are practically symmetrical.

We claim:

1. A system including apparatus for recovering oil from a subterraneanhydrocarbon-bearing formation by controllable insitu combustion wherebymeans are provided for regulating the injection of oxygen enriched gas,steam, and an exhaust gas containing carbon dioxide into said injectionwell comprising:

a. a combustion chamber for producing a gas-steam mixture having meansfor supplying thereto a fuel and an oxygen-containing gas, burner meansfor combustion of said fuel, a closed means for providing saidcombustion chamber with a first flow of water thereby generating steamin said closed means, a means for providing said combustion chamber witha second flow of water said means having nozzles directed into saidcombustion chamber, means for preheating said oxygencontaining gas, andmeans for exhausting said gassteam mixture from said combustion chamberinto a combustion turbine and thence into said injection well; a firstmeans for providing air to said system comprising a first source ofcompressed air in communication with an oxygen producing plant forproducing a highly concentrated oxygen stream, a compressor and a meansfor providing injection of said oxygen concentrated stream into saidinjection well; I

c. a second means for providing air to said system comprising an aircompressor in communication with said combustion chamber, said aircompressor being integral with a combustion turbine said combustionturbine being driven by said exhaust gases from said combustion chamberthereby generating power for said system of apparatus, and said firstair means and said second air means being in communication with eachother thereby to control the relative volumes of compressed air providedto said oxygen producing plant and said combustion chamber;

d. a means for providing water to said steam system comprising a watertreatment plant a first heat exchanger in communication with saidcombustion turbine for passage of said exhaust gases from saidcombustion turbine, a portion of said water from said treatment plantbeing supplied to said combustion chamber whereby steam generationoccurs in said combustion chamber and a second portion being supplied tosaid noules to supply steam in said combustion chamber said steam beinggenerated in said combustion chamber being thereafter supplied into asteam turbine to provide power generation and thence means for providingsaid steam to said injection well;

. means for providing said exhaust gas from said combustion chamber intosaid combustion turbine and to said first heat exchanger and thereafterproviding means for injection of said exhaust gas into said injectionwell.

2. A combustion chamber according to claim I having an external wall, aninterior wall and a tube supporting wall said tube supporting walltightly fitting to the bottom of said combustion chamber therebyproviding for the oxygen-containing air to be supplied to the burner ofsaid combustion chamber separately from the circulation system of thesteam and combustion gases.

3. A combustion chamber according to claim 1 wherein the tube supportingwall is provided with openings fitted with injectors to increase suctionof water vapors and combustion gases from the combustion chamber.

4. A combustion chamber according to claim 1 wherein said combustionchamber is fitted with first and second tube systems, separatelycontrolled, said first tube system being open and provided withinjection nozzles directed into said combustion chamber and said secondtube system being closed and separate from said combustion chamber forthe production of high pressure steam, said first and second tubesystems being provided with means for injecting water to controltemperature.

5. A combustion chamber according to claim 1 wherein said combustionchamber has a burner with horizontally superimposed burner elements anda central jet directed downward.

6. A combustion chamber according to claim 1 wherein said combustionchamber is fitted with exchangeable filter bodies for absorbing solid ordust-like particles.

1. A system including apparatus for recovering oil from a subterraneanhydrocarbon-bearing formation by controllable insitu combustion wherebymeans are provided for regulating the injection of oxygen enriched gas,steam, and an exhaust gas containing carbon dioxide into said injectionwell comprising: a. a combustion chamber for producing a gas-steammixture having means for supplying thereto a fuel and anoxygen-containing gas, burner means for combustion of said fuel, aclosed means for providing said combustion chamber with a first flow ofwater thereby generating steam in said closed means, a means forproviding said combustion chamber with a second flow of water said meanshaving nozzles directed into said combustion chamber, means forpreheating said oxygeN-containing gas, and means for exhausting saidgas-steam mixture from said combustion chamber into a combustion turbineand thence into said injection well; b. a first means for providing airto said system comprising a first source of compressed air incommunication with an oxygen producing plant for producing a highlyconcentrated oxygen stream, a compressor and a means for providinginjection of said oxygen concentrated stream into said injection well;c. a second means for providing air to said system comprising an aircompressor in communication with said combustion chamber, said aircompressor being integral with a combustion turbine said combustionturbine being driven by said exhaust gases from said combustion chamberthereby generating power for said system of apparatus, and said firstair means and said second air means being in communication with eachother thereby to control the relative volumes of compressed air providedto said oxygen producing plant and said combustion chamber; d. a meansfor providing water to said steam system comprising a water treatmentplant a first heat exchanger in communication with said combustionturbine for passage of said exhaust gases from said combustion turbine,a portion of said water from said treatment plant being supplied to saidcombustion chamber whereby steam generation occurs in said combustionchamber and a second portion being supplied to said nozzles to supplysteam in said combustion chamber said steam being generated in saidcombustion chamber being thereafter supplied into a steam turbine toprovide power generation and thence means for providing said steam tosaid injection well; e. means for providing said exhaust gas from saidcombustion chamber into said combustion turbine and to said first heatexchanger and thereafter providing means for injection of said exhaustgas into said injection well.
 2. A combustion chamber according to claim1 having an external wall, an interior wall and a tube supporting wallsaid tube supporting wall tightly fitting to the bottom of saidcombustion chamber thereby providing for the oxygen-containing air to besupplied to the burner of said combustion chamber separately from thecirculation system of the steam and combustion gases.
 3. A combustionchamber according to claim 1 wherein the tube supporting wall isprovided with openings fitted with injectors to increase suction ofwater vapors and combustion gases from the combustion chamber.
 4. Acombustion chamber according to claim 1 wherein said combustion chamberis fitted with first and second tube systems, separately controlled,said first tube system being open and provided with injection nozzlesdirected into said combustion chamber and said second tube system beingclosed and separate from said combustion chamber for the production ofhigh pressure steam, said first and second tube systems being providedwith means for injecting water to control temperature.
 5. A combustionchamber according to claim 1 wherein said combustion chamber has aburner with horizontally superimposed burner elements and a central jetdirected downward.
 6. A combustion chamber according to claim 1 whereinsaid combustion chamber is fitted with exchangeable filter bodies forabsorbing solid or dust-like particles.